Generally, perfluorooxyalkylene-containing compounds exhibit, by virtue of their extremely low surface free energy, excellent water/oil repellency, chemical resistance, lubricity, parting, antifouling and other properties. Taking advantage of these properties, they find use in a variety of industrial fields as water/oil repellent antifouling agents for paper and textiles, lubricants for magnetic recording media, oil-repellent agents for precision instruments, parting agents, cosmetic ingredients, protective films and the like. Inversely, the same properties indicate non-tackiness or non-adhesion to other substrates. Even if they can be coated to the substrate surface, it is difficult for the coating to tightly adhere thereto.
On the other hand, silane coupling agents are well known for their ability to bond organic compounds to surfaces of substrates of glass or fabric. They are widely used as surface coating agents for numerous substrates. The silane coupling agent contains an organic functional group and a reactive silyl group (typically alkoxysilyl) in the molecule. In the presence of airborne moisture or the like, the alkoxysilyl groups undergo self-condensation reaction to form a coating. As the alkoxysilyl groups form chemical and physical bonds with the surface of glass or metal, the coating becomes a tough coating having durability.
Patent Document 1 discloses a composition predominantly comprising a fluorooxyalkylene-containing polymer of the formula shown below. Lenses and antireflective coatings, when treated with fluorooxyalkylene-containing polymer-modified silane, are improved in lubricity, parting property and wear resistance, but lack weather resistance.
Herein Rf is —(CF2)d—(OC2F4)e(OCF2)f—O(CF2)d—, A is a monovalent fluorinated group terminated with a —CF3 group, Q is a divalent organic group, Z is a di- to octa-valent organopolysiloxane residue having a siloxane bond, R is an alkyl group having 1 to 4 carbon atoms or phenyl group, X is a hydrolyzable group, a is 2 or 3, b is an integer of 1 to 6, c is an integer of 1 to 5, α is 0 or 1, d is independently 0 or an integer of 1 to 5, e is an integer of 0 to 80, f is an integer of 0 to 80, the sum e+f is an integer of 5 to 100, and the repeating units may be randomly arranged.